1670s, templet "horizontal piece under a girder or beam," probably from French templet "weaver's stretcher," diminutive of temple, which meant the same thing, from Latin templum "plank, rafter," also "building for worship" (see temple (n.1)).

The meaning "pattern or gauge for shaping a piece of work" is first recorded 1819 in this form, earlier temple (1680s); the form was altered 1844, probably influenced by plate, but the pronunciation did not begin to shift until much more recently.